1. Field of the Invention:
The present invention relates to a method for producing a non-woven fabric. Particularly, the present invention relates to a method for producing a non-woven fabric of regenerated cellulose fibers.
2. Description of the Prior Art:
Spun-bond techniques have recently been introduced in the field of polyolefin, polyamide, and polyester fibers which combined the step of melt spinning and the step of web formation. In this technique, the fibers obtained by the melt spinning are directly formed into a web and then the web is subjected to a heat pressing treatment to produce a self-coherent fibrous sheet material. Since aftertreatments, such as washing and bleaching of the web, are usually unnecessary in this technique, the steps subsequent to the web formation are comparably simple so that the fibrous sheet materials can be easily produced at a high rate of productivity.
On the other hand, a method described as a wet spun-bond technique is able to produce fibrous sheet materials by the step of web formation in succession to the wet spinning of the fiber. This method is applicable to viscose, cuprammonium rayon, or acrylonitrile fibers.
One of the problems in the wet spun-bond technique is the necessity to perform regeneration, and after treatments such as treatment(s) for completion of regeneration, desulfurization, and bleaching of the web in the case of viscose fibers and washing of the web to wash off the remaining solvent in the case of acrylonitrile fibers, and thus the space to be occupied by the apparatus for the aftertreatments becomes so large that problems occur in improving productivity per unit area occupied by the apparatus. Moreover, as a change in the size of the web will be caused by regeneration, washing, and the like treatments, close attention is required in the control of tension applied to the web. Sophisticated tension control requires expensive apparatus. Further, it is difficult to produce economically a sheet material of low weight unless the feeding speed of the web is markedly increased. As apparent, previous wet spun-bond techniques have appreciable shortcomings.